[openib-general] heads-up - ipoib NAPI

[Shirley Ma]

Hi, Eli,

> Hi,
> I have a draft implementation of NAPI in ipoib and got the following
> results:
> System descriptions
> ===================
> Quad CPU E64T 2.4 Ghz
> 4 GB RAM
> MT25204 Sinai HCA
> I used netperf for benchmarking, the BW test ran for 600 seconds with 8
> clients and 8 servers.
>
> The results I received are bellow:
>
> netperf TCP_STREAM:
>       BW [MByte/sec]    clients side [irqs/sec]   server side [irqs/sec]
>       --------------    -----------------------   ----------------------
> without NAPI:       506                    86441                   66311
> with NAPI:          550                     6830                   13600
>
>
> netperf TCP_RR:
>       rate [tran/sec]
>                 ---------------
> without NAPI:      39600
> with NAPI:         39470
>
>
>
> Please note this is still under work and we plan to do more tests and
> measure on other devices.

NAPI patch moves ipoib poll from hardware interrupt context to softirq
context. It would reduce the hardware interrupts, reduce hardware latency
and induce some network latency. It might reduce cpu utilization. But I
still question about the BW improvement. I did see various performance with
the same test under the same condition.

Have you tested this patch with different message sizes, different socket
sizes? Are these results consistent better?

Thanks
Shirley Ma
IBM Linux Technology Center
15300 SW Koll Parkway
Beaverton, OR 97006-6063
Phone(Fax): (503) 578-7638
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